US4612179A - Process for purification of solid silicon - Google Patents

Process for purification of solid silicon Download PDF

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Publication number
US4612179A
US4612179A US06/711,584 US71158485A US4612179A US 4612179 A US4612179 A US 4612179A US 71158485 A US71158485 A US 71158485A US 4612179 A US4612179 A US 4612179A
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United States
Prior art keywords
silicon
purifying agent
purifying
sodium
lithium
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Expired - Fee Related
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US06/711,584
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English (en)
Inventor
Angel Sanjurjo
Sylvia Pressacco
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SRI International Inc
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SRI International Inc
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Assigned to SRI INTERNATIONAL reassignment SRI INTERNATIONAL ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SANJURJO, ANGEL, PRESSACCO, SYLVIA
Priority to US06/711,584 priority Critical patent/US4612179A/en
Priority to DE19863690134 priority patent/DE3690134T1/de
Priority to EP86902962A priority patent/EP0215121B1/en
Priority to GB8624297A priority patent/GB2179644B/en
Priority to PCT/US1986/000499 priority patent/WO1986005475A1/en
Priority to NL8620174A priority patent/NL8620174A/nl
Priority to JP61502717A priority patent/JPS62502319A/ja
Priority to US07/009,326 priority patent/US4828814A/en
Priority to AU60918/86A priority patent/AU590311B2/en
Publication of US4612179A publication Critical patent/US4612179A/en
Application granted granted Critical
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/037—Purification
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/14—Refining in the solid state
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S423/00—Chemistry of inorganic compounds
    • Y10S423/09—Reaction techniques
    • Y10S423/12—Molten media

Definitions

  • This invention relates to a process for the purification of silicon. More particularly, this process relates to a process for purifying solid silicon which has been heated to a temperature slightly below the melting point of silicon while contacting the heated silicon with a purifying agent which does not appreciably react with the silicon.
  • Pruvot et al U.S. Pat. No. 3,034,886 describes the purification of silicon or ferrosilicons by the injection of silicon fluoride gas into the liquid bath to react with aluminum and calcium impurities to form aluminum and calcium fluorides.
  • Boulos U.S. Pat. No. 4,379,777 teaches passing powdered silicon through a plasma which apparently causes migration of the impurities to the surface of the molten silicon particles. After quenching, the particles are acid-leached to remove the surface impurities.
  • Kapur et al U.S. Pat. No. 4,388,286 combines vacuum refining of silicon with mixing the silicon with an effective fluxing agent, such as a fluoride of an alkali metal or an alkaline earth metal, to form a molten silicon phase and a slag phase.
  • an effective fluxing agent such as a fluoride of an alkali metal or an alkaline earth metal
  • an object of the invention to provide a process for the purification of solid silicon to a purity of 99.999 or better.
  • a process for producing silicon having a purity as high as 99.9999% comprises contacting solid silicon at a temperature slightly below the melting point of silicon with a molten purifying agent which does not appreciably react with silicon to cause the impurities in the silicon to enter the material.
  • the sole figure is a flow sheet illustrating the process of the invention.
  • the process of the invention involves the initial provision of a source of silicon which is crushed into particulate form, heated to just below the melting point of the silicon, and then contacted at this temperature with a purifying agent which will extract the impurities without substantially reacting with the silicon, cooling the mixture, and then solubilizing the impurity rich purifying compound leaving silicon having a purity of 99.999 or better which is recovered by decantation and/or filtration.
  • the silicon used in the process may be an already partially purified silicon, or may be metallurgical grade silicon.
  • the silicon starting material should be at least 98-99% pure.
  • the silicon is crushed to a particle size range of equal to or smaller than 0.1 mm to 1 mm in at least one direction, i.e., smaller than the grain size in metallurgical grade silicon, to thereby expose most of the grain boundaries in which much of the impurities in the solid silicon will be concentrated.
  • the particulate silicon may be optionally prepurified in an acid leaching step, for example, with an acid mixture, such as HNO 3 --HF or H 2 O 2 --HF for a period of 10-60 minutes.
  • an acid mixture such as HNO 3 --HF or H 2 O 2 --HF for a period of 10-60 minutes.
  • the temperature may vary from room temperature to slightly under the boiling point of the acid mixture. If higher temperatures are used, the reaction time should be correspondingly shortened.
  • the silicon particles are mixed with the purifying agent in a ratio of from 0.1:2 to 2:1, preferably about 1:1.
  • the purifying agent is selected to be a material which will react with the typical impurities found in silicon, such as iron and aluminum and, to a lesser extent, calcium, chromium, and nickel, but will be substantially nonreactive with silicon.
  • substantially nonreactive is meant that less than 0.01% will react with silicon at the purification temperature.
  • the purifying agent may comprise an oxide of silicon, including silicon oxide or a silicate or halide of lithium, sodium, potassium, magnesium, strontium, calcium, or barium which substantially is nonreactive with silicon.
  • Especially preferred materials are SiO 2 , NaF, and Na 2 SiO 3 both because of their effectiveness and the material cost.
  • the purifying agent should be at least of reagent grade purity. However, in one embodiment, the purifying agent is preselected to contain a doping agent for the silicon in an amount to permit tailoring of the resistivity of the final purified silicon product.
  • the purifying agent is preferably ground to a particle size range approximating the particulate silicon to facilitate thorough mixing of the materials.
  • the particulate silicon and purifying agent are then heated to a temperature of at least about 1300° C. and, preferably, to just under the melting point of silicon, i.e., just under 1420° C.
  • just under the melting point of silicon is meant about 1400°-1410° C.
  • the mixture is placed in a containment vessel which will not react with the silicon or cause impurities therein to migrate into the silicon at the purification temperature.
  • a containment vessel may comprise a SiO 2 , SiC or Si 3 N 4 material or at least a vessel lined with one of these materials.
  • a graphite vessel may also be used under certain circumstances where the carbon will not react with the silicon, e.g., in the presence of a NaF purifying agent.
  • the materials are held at the purification temperature for a period of time which may range from as short as 15 minutes to as long as 3 hours depending upon the reactivity of the purification agent.
  • a period of time which may range from as short as 15 minutes to as long as 3 hours depending upon the reactivity of the purification agent.
  • SiO 2 such as silica gel
  • NaF can be used for 15 minutes or Na 2 SiO 3 for 30 minutes.
  • the purifying agent is liquid, then it may be added and removed continuously until the desired purification has been achieved. In general, the mixture is then cooled to room temperature, and the now purified silicon is recovered by leaching the solidified mixture with a reagent which is a solvent for the impurity-rich purifying agent but which will not appreciably attack the silicon. Concentrated, or at least 5%, HF has been found to be a satisfactory leaching agent.
  • the leaching agent should preferably be at least as pure as the final desired purity of the silicon to avoid introduction of contamination after the high temperature purification step.
  • An electronic grade HF is satisfactory in a final leach although less pure, i.e., commercial grade, HF can be used in a first leach.
  • the purified silicon is recovered by separating the solid silicon from the now solubilized purification agent, such as by decantation or filtration.
  • the purified silicon may be subject to a further purification step to remove sodium. This may be accomplished by heating the silicon in vacuum to a temperature of 800° C. or higher for about 5 to 60 minutes. Alternatively, the sodium may be oxidized and then the oxide layer removed by leaching in HF.
  • the process of the invention may also be operated on a continuous basis if desired wherein the silicon and purifying agent are continuously fed into a reactor as a particulate mixture and the treated materials continuously removed from the reactor.
  • the silicon and purifying agent are continuously fed into a reactor as a particulate mixture and the treated materials continuously removed from the reactor.
  • thin sheets or a ribbon of silicon can be used instead of crushed silicon particles.
  • silicon can be continuously fed through a pool of molten purifying agent thus permitting direct use of the purified silicon product in the manufacture of electronic devices, such as solar cells.
  • Metallurgical grade silicon with a particle size of less than 1 mm was heated with an equal amount of spectrographic grade SiO 2 gel in a graphite crucible to 1360° C. for 180 minutes under an Ar atmosphere. After cooling to room temperature, the Si-SiO 2 mixture was leached with concentrated HF.
  • the impurities (in parts per million) of the initial metallurgical grade silicon and the purified silicon are shown in Table 1.
  • Example II The same silicon as in Example I was mixed with an equal amount of reagent grade Na 2 SiO 3 . The mixture was heated in a graphite crucible at 1360° C. for 30 minutes under an Ar atmosphere. After cooling, the mixture of Si-Na 2 SiO 3 was leached with concentrated HF. The impurities (in parts per million) of the initial metallurgical grade silicon and the purified Si are shown in Table 2.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)
US06/711,584 1985-03-13 1985-03-13 Process for purification of solid silicon Expired - Fee Related US4612179A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US06/711,584 US4612179A (en) 1985-03-13 1985-03-13 Process for purification of solid silicon
PCT/US1986/000499 WO1986005475A1 (en) 1985-03-13 1986-03-07 Process for purification of solid material
EP86902962A EP0215121B1 (en) 1985-03-13 1986-03-07 Process for purification of solid material
GB8624297A GB2179644B (en) 1985-03-13 1986-03-07 Process for purification of solid material
DE19863690134 DE3690134T1 (ko) 1985-03-13 1986-03-07
NL8620174A NL8620174A (nl) 1985-03-13 1986-03-07 Werkwijze voor de zuivering van vaste stof.
JP61502717A JPS62502319A (ja) 1985-03-13 1986-03-07 固体材料の精製方法
US07/009,326 US4828814A (en) 1985-03-13 1986-03-07 Process for purification of solid material
AU60918/86A AU590311B2 (en) 1985-03-13 1986-08-06 Process for purification of solid material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/711,584 US4612179A (en) 1985-03-13 1985-03-13 Process for purification of solid silicon

Related Child Applications (1)

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US07/009,326 Continuation-In-Part US4828814A (en) 1985-03-13 1986-03-07 Process for purification of solid material

Publications (1)

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US4612179A true US4612179A (en) 1986-09-16

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US06/711,584 Expired - Fee Related US4612179A (en) 1985-03-13 1985-03-13 Process for purification of solid silicon
US07/009,326 Expired - Fee Related US4828814A (en) 1985-03-13 1986-03-07 Process for purification of solid material

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Country Status (8)

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US (2) US4612179A (ko)
EP (1) EP0215121B1 (ko)
JP (1) JPS62502319A (ko)
AU (1) AU590311B2 (ko)
DE (1) DE3690134T1 (ko)
GB (1) GB2179644B (ko)
NL (1) NL8620174A (ko)
WO (1) WO1986005475A1 (ko)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4828814A (en) * 1985-03-13 1989-05-09 Sri International Process for purification of solid material
US6059887A (en) * 1997-04-03 2000-05-09 Purex Co., Ltd. Process for cleaning the interior of semiconductor substrate
WO2004029332A2 (en) * 2002-09-25 2004-04-08 Qinetiq Limited Purification of electrochemically deoxidised refractory metal particles by heat processing
WO2005061383A1 (en) * 2003-12-04 2005-07-07 Dow Corning Corporation Method of removing impurities from metallurgical grade silicon to produce solar grade silicon
US20070248521A1 (en) * 2006-04-13 2007-10-25 Cabot Corporation Production of silicon through a closed-loop process
US20070245854A1 (en) * 2006-04-25 2007-10-25 The Arizona Board Of Regents On Behalf Of The University Of Arizona Silicon refining process
WO2008062204A1 (en) * 2006-11-22 2008-05-29 Intrinsiq Materials Limited Purification method
US20080206123A1 (en) * 2003-12-29 2008-08-28 Elkem Asa Silicon feedstock for solar cells
US20090074647A1 (en) * 2007-09-14 2009-03-19 General Electric Company System and method for producing solar grade silicon
US20090130015A1 (en) * 2005-06-29 2009-05-21 Sumitomo Chemical Company, Limited Method for producing high purity silicon
WO2010041077A2 (en) * 2008-10-08 2010-04-15 Intrinsiq Materials Limited Nanoparticle purification
US20100178195A1 (en) * 2007-06-08 2010-07-15 Motoyuki Yamada Method of solidifying metallic silicon
CN101085678B (zh) * 2006-06-09 2010-11-10 贵阳宝源阳光硅业有限公司 太阳能级硅的制备方法
US20100329959A1 (en) * 2007-07-23 2010-12-30 6N Silicon Inc. Use of acid washing to provide purified silicon crystals
ITPD20090254A1 (it) * 2009-09-07 2011-03-08 Estelux S R L Processo di purificazione del silicio
US20110129405A1 (en) * 2006-04-04 2011-06-02 6N Silicon Inc. Method for purifying silicon
US8801855B2 (en) 2007-10-03 2014-08-12 Silicor Materials Inc. Method for processing silicon powder to obtain silicon crystals
EP2480497A4 (en) * 2009-09-23 2016-06-15 Elkem Solar As PROCESS FOR THE PRODUCTION OF HIGH-PURITY SILICON
US9567227B2 (en) 2009-07-03 2017-02-14 Mitsubishi Chemical Corporation Process for producing silicon, silicon, and panel for solar cells
RU2702173C1 (ru) * 2018-12-25 2019-10-04 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет" Способ повышения эффективности очистки кремния

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NO165288C (no) * 1988-12-08 1991-01-23 Elkem As Silisiumpulver og fremgangsmaate for fremstilling av silisiumpulver.
US5208001A (en) * 1991-06-20 1993-05-04 Texas Instruments Incorporated Method for silicon purification
US5346563A (en) * 1991-11-25 1994-09-13 United Technologies Corporation Method for removing sulfur from superalloy articles to improve their oxidation resistance
NO174165C (no) * 1992-01-08 1994-03-23 Elkem Aluminium Fremgangsmåte ved kornforfining av aluminium samt kornforfiningslegering for utförelse av fremgangsmåten
WO1997003922A1 (fr) * 1994-01-10 1997-02-06 Showa Aluminum Corporation Procede pour produire du silicium tres pur
NO180532C (no) * 1994-09-01 1997-05-07 Elkem Materials Fremgangsmåte for fjerning av forurensninger fra smeltet silisium
CN1083396C (zh) * 1995-07-14 2002-04-24 昭和电工株式会社 高纯度硅的制造方法
US6790419B1 (en) * 1999-06-11 2004-09-14 Honeywell Intellectual Properties Inc. Purification of gaseous inorganic halide
NO313132B1 (no) * 1999-12-08 2002-08-19 Elkem Materials Fremgangsmåte for rensing av silisium
WO2003066523A1 (fr) * 2002-02-04 2003-08-14 Sharp Kabushiki Kaisha Procede de purification du silicium, scories pour purifier le silicium et silicium purifie
US8021483B2 (en) 2002-02-20 2011-09-20 Hemlock Semiconductor Corporation Flowable chips and methods for the preparation and use of same, and apparatus for use in the methods
US7959707B2 (en) * 2006-04-28 2011-06-14 Sri International Methods for producing consolidated materials
CN100449791C (zh) * 2006-05-26 2009-01-07 华东师范大学 化合物半导体层的制作方法及使用该半导体层的太阳能电池及其制作方法
WO2008026728A1 (fr) * 2006-08-31 2008-03-06 Mitsubishi Materials Corporation Silicium métallique et son procédé de fabrication
CN102037156B (zh) * 2008-03-05 2013-09-04 Sri国际公司 太阳能电池的基板和其生产方法
US8475540B2 (en) * 2009-08-12 2013-07-02 Sri International Multi-stage system for reaction and melt coalescence and separation
CN101792143B (zh) * 2010-03-24 2011-12-21 姜学昭 提纯硅的方法
US9656873B2 (en) 2013-11-21 2017-05-23 Kennametal Inc. Purification of tungsten carbide compositions
BR112017016492B1 (pt) * 2015-01-30 2022-09-20 Advanced Accelerator Applications International S.A.. Processo para a purificação de ga-68 a partir de eluato que deriva de geradores de 68ge/ 68ga e colunas cromatográficas para uso no dito processo

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Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4828814A (en) * 1985-03-13 1989-05-09 Sri International Process for purification of solid material
US6059887A (en) * 1997-04-03 2000-05-09 Purex Co., Ltd. Process for cleaning the interior of semiconductor substrate
US20060130610A1 (en) * 2002-09-25 2006-06-22 Ward-Close Charles M Purification process
WO2004029332A2 (en) * 2002-09-25 2004-04-08 Qinetiq Limited Purification of electrochemically deoxidised refractory metal particles by heat processing
WO2004029332A3 (en) * 2002-09-25 2004-10-21 Qinetiq Ltd Purification of electrochemically deoxidised refractory metal particles by heat processing
US20070202029A1 (en) * 2003-12-04 2007-08-30 Gary Burns Method Of Removing Impurities From Metallurgical Grade Silicon To Produce Solar Grade Silicon
WO2005061383A1 (en) * 2003-12-04 2005-07-07 Dow Corning Corporation Method of removing impurities from metallurgical grade silicon to produce solar grade silicon
US20080206123A1 (en) * 2003-12-29 2008-08-28 Elkem Asa Silicon feedstock for solar cells
US7931883B2 (en) * 2003-12-29 2011-04-26 Elkem As Silicon feedstock for solar cells
US20090130015A1 (en) * 2005-06-29 2009-05-21 Sumitomo Chemical Company, Limited Method for producing high purity silicon
US20110129405A1 (en) * 2006-04-04 2011-06-02 6N Silicon Inc. Method for purifying silicon
US20070248521A1 (en) * 2006-04-13 2007-10-25 Cabot Corporation Production of silicon through a closed-loop process
US7780938B2 (en) * 2006-04-13 2010-08-24 Cabot Corporation Production of silicon through a closed-loop process
US7682585B2 (en) 2006-04-25 2010-03-23 The Arizona Board Of Regents On Behalf Of The University Of Arizona Silicon refining process
US20070245854A1 (en) * 2006-04-25 2007-10-25 The Arizona Board Of Regents On Behalf Of The University Of Arizona Silicon refining process
CN101085678B (zh) * 2006-06-09 2010-11-10 贵阳宝源阳光硅业有限公司 太阳能级硅的制备方法
WO2008062204A1 (en) * 2006-11-22 2008-05-29 Intrinsiq Materials Limited Purification method
GB2457616A (en) * 2006-11-22 2009-08-26 Intrinsiq Materials Global Ltd Purification method
US20100015028A1 (en) * 2006-11-22 2010-01-21 Daniel Johnson Purification method
US20100178195A1 (en) * 2007-06-08 2010-07-15 Motoyuki Yamada Method of solidifying metallic silicon
US20100329959A1 (en) * 2007-07-23 2010-12-30 6N Silicon Inc. Use of acid washing to provide purified silicon crystals
US8480991B2 (en) * 2007-07-23 2013-07-09 Silicor Materials Inc. Use of acid washing to provide purified silicon crystals
US20090074647A1 (en) * 2007-09-14 2009-03-19 General Electric Company System and method for producing solar grade silicon
US7572425B2 (en) 2007-09-14 2009-08-11 General Electric Company System and method for producing solar grade silicon
US8801855B2 (en) 2007-10-03 2014-08-12 Silicor Materials Inc. Method for processing silicon powder to obtain silicon crystals
WO2010041077A2 (en) * 2008-10-08 2010-04-15 Intrinsiq Materials Limited Nanoparticle purification
WO2010041077A3 (en) * 2008-10-08 2010-08-26 Intrinsiq Materials Limited Nanoparticle purification
US9567227B2 (en) 2009-07-03 2017-02-14 Mitsubishi Chemical Corporation Process for producing silicon, silicon, and panel for solar cells
ITPD20090254A1 (it) * 2009-09-07 2011-03-08 Estelux S R L Processo di purificazione del silicio
EP2480497A4 (en) * 2009-09-23 2016-06-15 Elkem Solar As PROCESS FOR THE PRODUCTION OF HIGH-PURITY SILICON
RU2702173C1 (ru) * 2018-12-25 2019-10-04 Федеральное государственное бюджетное образовательное учреждение высшего образования "Рязанский государственный радиотехнический университет" Способ повышения эффективности очистки кремния

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Publication number Publication date
NL8620174A (nl) 1987-02-02
AU590311B2 (en) 1989-11-02
GB8624297D0 (en) 1986-11-12
JPS62502319A (ja) 1987-09-10
US4828814A (en) 1989-05-09
AU6091886A (en) 1988-02-11
EP0215121B1 (en) 1991-07-03
GB2179644B (en) 1989-12-20
WO1986005475A1 (en) 1986-09-25
GB2179644A (en) 1987-03-11
DE3690134T1 (ko) 1987-03-12
EP0215121A1 (en) 1987-03-25

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